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  • 1
    Electronic Resource
    Electronic Resource
    Gas permeation and viscoelastic deformation of prepregs in composite manufacturing processes (1995)
    Brookfield, Conn. : Wiley-Blackwell
    Polymer Composites 16 (1995), S. 370-377 
    Details
    ISSN: 0272-8397
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Gas permeation and creep deformation of a commercial prepreg, which exhibits viscoelastic characteristics, were investigated as a function of time, temperature, and consolidation pressure. Experiments using a prepreg stack demonstrated that the material exhibited a linear viscoelastic bulk deformation under vacuum/autoclave pressure and furthermore, the in-plane gas flow exhibited non-Darcian flow behavior with a permeation hysteresis. This behavior was viewed and analyzed by two viscoelastic relaxation processes: (1) bulk dimensional relaxation, and (2) microscopic pore structure rearrangement. A modified standard linear solid (SLS) viscoelastic model was used to interpret the creep compliance and dynamic gas permeability utilizing two independent relaxation parameters. By visual investigation of pore sizes and their distribution, air permeation was found to take place mostly through the interlaminar porosity network for the prepreg system examined.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pc.750160505
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  • 2
    Electronic Resource
    Electronic Resource
    Comparison of two carboxylate-activating agents for the modification of a synthetic heparinoid polyelectrolyte (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Letters Edition 21 (1983), S. 1-11 
    Details
    ISSN: 0360-6384
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1983.130210101
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  • 3
    Electronic Resource
    Electronic Resource
    Lifting aerofoil calculation using the boundary element method (1983)
    Chichester : Wiley-Blackwell
    International Journal for Numerical Methods in Fluids 3 (1983), S. 481-491 
    Details
    ISSN: 0271-2091
    Keywords: Boundary Elements ; Lifting Aerofoil ; Potential Flow ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The bbundary integral formulation and boundary element method are extended to include lifting flow problems. This involves inclusion of a branch cut in the flow field and imposition of a Kutta condition to determine the circulation, Γ Additional boundary integral contributions arise from the cut surface. Techniques for calculating Γ are developed and we treat, in particular, a superposition procedure which permits very efficient computation. Numerical results are presented for an NACA0012 aerofoil at several angles of attack.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/fld.1650030504
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  • 4
    Electronic Resource
    Electronic Resource
    Velocity-pressure integrated versus penalty finite element methods for high-Reynolds-number flows (1989)
    Chichester : Wiley-Blackwell
    International Journal for Numerical Methods in Fluids 9 (1989), S. 43-57 
    Details
    ISSN: 0271-2091
    Keywords: Finite element ; Penalty method ; Consistent penalty ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Velocity-pressure integrated and consistent penalty finite element computations of high-Reynolds-number laminar flows are presented. In both methods the pressure has been interpolated using linear shape functions for a triangular element which is contained inside the biquadratic flow element. It has been shown previously that the pressure interpolation method, when used in conjunction with the velocity-pressure integrated method, yields accurate computational results for high-Reynolds-number flows. It is shown in this paper that use of the same pressure interpolation method in the consistent penalty finite element method yields computational results which are comparable to those of the velocity-pressure integrated method for both the velocity and the pressure fields. Accuracy of the two finite element methods has been demonstrated by comparing the computational results with available experimental data and/or fine grid finite difference computational results. Advantages and disadvantages of the two finite element methods are discussed on the basis of accuracy and convergence nature. Example problems considered include a lid-driven cavity flow of Reynolds number 10 000, a laminar backward-facing step flow and a laminar flow through a nest of cylinders.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/fld.1650090105
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  • 5
    Electronic Resource
    Electronic Resource
    Chlorinated hydrocarbon coupling agents for mica-polypropylene composites (1982)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 27 (1982), S. 4179-4189 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The incorporation of small amounts of a chlorinated hydrocarbon wax into polypropylene (PP) when making mica-PP composites is shown to produce a layer of degraded chlorinated hydrocarbon at the interface between the polymer and the reinforcement. Mica is shown to accelerate the thermal degradation of the chlorinated hydrocarbon, and the chlorinated hydrocarbon, or its degradation products, are shown to react with hydrocarbon analogues of the polymer. As well as modify the chemical nature of the interface, the layer of degraded chlorinated hydrocarbon is shown to modify the morphology of the interface by inhibiting the ability of the mica to nucleate the crystallization of PP from the melt.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1982.070271109
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  • 6
    Electronic Resource
    Electronic Resource
    Synthesis and characterization of polystyrene-poly(ethylene oxide)-heparin block copolymers (1988)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 26 (1988), S. 381-391 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A procedure for the preparation of new block copolymers composed of a hydrophobic block of polystyrene, a hydrophilic spacer-block of poly(ethylene oxide) and a bioactive block of heparin was investigated. Polystyrene with one amino group per chain was synthesized by free radical oligomerization of styrene in dimethylformamide, using 2-aminoethanethiol as a chain transfer agent. This amino group was used in the coupling reaction with amino-telechelic poly(ethylene oxide) to produce an AB type diblock copolymer with one amino group per polystyrene (PSt)-poly(ethylene oxide) (PEO) chain. The amino-semitelechelic oligo-styrene was converted into the isocyanate-semitelechelic oligo-styrene using toluene 2,4-diisocyanate and subsequent coupling with H2N-PEO-NH2 afforded AB type block copolymers with terminal amino groups. The coupling of PSt-PEO-NH2 with heparin was performed in a DMF-H2O mixture, first by activating the heparin carboxylic groups with EDC at pH 5.1-5.2 and subsequently reacting the activated carboxylic groups with the amino groups of the PSt-PEO-NH2 at pH 7.5. Depending on the molecular weights of the diblock copolymer used 25-29% w/w heparin was incorporated. These polymers will be further evaluated for their blood-compatibility.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1988.080260204
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  • 7
    Electronic Resource
    Electronic Resource
    Synthesis and characterization of polystyrene-poly(ethylene oxide)-heparin block copolymers (1989)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 27 (1989), S. 397-397 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1989.080270135
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  • 8
    Electronic Resource
    Electronic Resource
    Improved synthesis of polystyrene-poly(ethylene oxide)-heparin block copolymers (1990)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 28 (1990), S. 1693-1720 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A novel procedure for the synthesis of block copolymers composed of a hydrophobic block of polystyrene, a hydrophilic block of poly(ethylene oxide) and a bioactive block of nitrous acid-degraded heparin was developed. Amino-semitelechelic polystyrene was prepared by anionic polymerization of styrene in cyclohexane, using sec-butyllithium as initiator and N-(benzylidene)trimethylsilylamide as terminator. After purification using preparative column chromatography, polystyrene with one amino group per chain and a narrow molecular weight distribution was obtained. The terminal amino group was used in the coupling reaction with amino-telechelic poly(ethylene oxide) using toluene 2,4-diisocyanate to produce amino-semitelechelic polystyrene-poly(ethylene oxide) diblock copolymer (PS-PEO-NH2). The block copolymer was purified by preparative column chromatographic separations and had a narrow molecular weight distribution. Approximately one amino group per chain was found. When methylene 4,4′-diphenyl diisocyanate or hexamethylene diisocyanate were used as coupling agents low yields of PS-PEO-NH2 were obtained. Polystyrene-poly(ethylene oxide)-heparin triblock copolymer was synthesized in a DMF-H20 (40:1, v/v) mixture by a coupling reaction of PS-PEO-NH2 with nitrous acid-degraded heparin, in which aldehyde groups react with the primary amino groups of PS-PEO-NH2 at pH 7 in the presence of NaBH3CN via reductive amination. Using this procedure, 18-32% w/w heparin was incorporated, corresponding to ±1 PS-PEO chain per heparin molecule. These procedures enable the synthesis of well defined heparin containing block copolymers, which will be further evaluated for thier blood compatibility.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1990.080280704
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  • 9
    Electronic Resource
    Electronic Resource
    Enhanced polycarbonate toughness. II: Mechanisms (1995)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 35 (1995), S. 477-482 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Glassy shell-rubbery core polymer particles, 0.1 to 0.2 μm in diameter, increase the plane strain JIC values of 3.175 mm thick polycarbonate from 3.05 kJ/m2 (no particles) to 9.5 kJ/m2 (7.5 phr particles) at 23°C. Some modest decreases in these values are caused by tests at -20°C in samples 9.525 and 3.175 mm thick. If only the particle concentration is varied, JIC increases monotonically to 7.5 phr (by wt), then levels off or decreases slightly at 10.0 phr. The total volume of 1 to 2 μm diameter cavities formed in the matrix by the apparently unbonded particles behaves similarly; cavity volume and JIC are directly related. With increasing particle concentration the tensile modulus is unchanged, the yield stress and strain decrease modestly, the strain at fracture decreases appreciably, and the heat recoverable orientation in the fractured samples decreases. Few cavities are formed. The particles reduce the extent of shear deformation in the tensile samples.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760350604
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  • 10
    Electronic Resource
    Electronic Resource
    Enhanced polycarbonate toughness. I: Measurement methodology (1995)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 35 (1995), S. 471-476 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The JIC values for core-shell-particle-toughened polycarbonate were determined at different temperatures and at 0, 2.5, 5.0, 7.5, and 10.0 phr particle content by six similar methods, using compact tensile specimens. At the 2.5 phr toughener level, the JIC values ranged from 2878 to 6100 J/m2, and at 7.5 phr, they ranged from 6125 to 10,760 J/m2, dependent only upon how the same JI-Δ a data were interpreted. This indicates that more work will be required before a reliable method of JIC measurement that can be applied to tough polymers is achieved.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760350603
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